In the field of electrical lighting, many different types of light sources have been developed over the years. Recently, fluorescent light fixtures have been developed to take advantage of the greater electrical efficiency provided by such lights.
To prevent self-destruction, conventional fluorescent lamps must use a ballast to regulate the current flow through the lamp's glass tubes. However, when the ballasts and other components break down and require replacement, repair of the fluorescent light can be costly in terms of both parts and labor. Also, disposal of fluorescent lamps raises environmental issues because of their mercury content.
To address the problems associated with fluorescent lamps, LED lamps are now widely accepted as a more efficient and environmental friendly light source than fluorescent lamps. LED lamps allow electrical current to pass through the device in one direction while blocking current flow in the opposite direction. LED lamps provide many advantages as a lighting alternative compared to fluorescent lamps. Some benefits of using LED lamps include no mercury, operation in extreme cold conditions, longer life, and better energy efficiency.
To satisfy the required UL 1598C standards and to leverage the benefits of the fluorescent lights, most lighting manufacturers produce retrofit kits to install LED components in existing light fixtures. However, many of these kits require modification to the existing fixtures, and some still potentially create the risk of fire and shock. Often, highly trained technicians are required to perform these modifications. Thus, retrofitting and rewiring existing fluorescent fixtures can be quite expensive and dangerous. Some manufacturers produce safety switches to protect against the risk of shock.
In addition to addressing the risk of shock, efforts have been made by lighting manufacturers to provide a LED lamp that is simple enough for ordinary consumers to replace. Another problem associated with replacing fluorescent lamps is that each type of fluorescent lamp is designed with different electronic ballasts to properly start and operate the lamp.
Many of the existing replacement solutions, for example, work only with switch start magnetic ballasts. The switch start magnetic ballast replacement LED replacement solution, however, requires fixture modification, as will be described in further detail below. Many of the geographic territories in which these approaches are most needed do not permit fixture modifications.
By way of background, there are hundreds of different types of fluorescent lamps including different types of ballasts available on the market, which requires ballast manufacturers to carry an expansive inventory of ballast types. The most common electromagnetic ballasts are switch start (preheat), rapid start, program start, and instant start.
A switch start (preheat) electromagnetic ballast uses a combination filament-cathode at each end of the lamp in conjunction with a starter switch that initially connects the filaments in series with the ballast, thereby preheating the filaments prior to striking an arc tube. The starter switch closes, permitting a heating current to flow through each electrode. The starter switch triggers the supply voltage to be applied across the arc tube to initiate the discharge. The electrode heating power is turned off after the lamp discharge is initiated.
A rapid start electronic ballast uses filament power windings within the ballast to provide a low voltage to the lamp prior to lamp ignition. The ballast applies voltage and heats the cathode simultaneously. The rapid start electronic ballast continues to heat the lamp electrodes even after the lamp is started.
Program start electronic ballasts include circuitry to preheat the lamp filaments to apply cathode heat before lamp ignition, and then remove it once the lamp is ignited. The ballast applies power to the filaments first, then after a short delay to allow the cathodes to preheat, applies voltage to the lamps to strike an arc.
Instant start electronic ballasts do use filaments to provide ignition. The ballasts of these tubes do not preheat the electrodes. Rather, they use a high voltage to break down the gas and mercury column to initiate the discharge arc. These tubes can be identified by a single pin at each end of the tube or a shunted lamp holder.
None of the above-described electronic ballasts have a robust, straightforward solution for enabling the design of LFL replacement LED lamps. Although limited solutions exist, each of these approaches requires some level of modification of the lamp's fixture. In the absence of such a solution, the market for LFL replacement LEDs will remain limited.